As one of the Bluetooth (registered trademark: abbreviated as “BT” hereinafter) standard communication protocols, Advanced Audio Distribution Profile (A2DP) is available for controlling packet transfer of music streamlining data. A2DP transfers the music streaming data by compressing the data on the transferring side in Sub-band Coding (SBC) format, MP3 (MPEG Audio Layer-3) format, Adaptive Transform Acoustic Coding format or the like in a unit of packets, as shown, for example, in Japanese patent document JP-A-2003-309541.
BT devices having BT communication capability are configured to continuously transmit a page command to a requesting BT device until the requesting device responds to the page command, or for a preset page command transmission time of, for example, 5.12 seconds, when a BT device generates a request for a BT connection link. On the other hand, some of the BT devices are capable of establishing multiple BT connection links with multiple BT devices at the same time in recent years. The BT capable cellular phones and BT capable music players are the examples of the so-called multi-connection BT devices.
In view of the above-described situations, there is a case that the multi-connection BT handsfree apparatus for use in a vehicle with a BT cellular phone and a BT audio player brought into a vehicle compartment at the same time has a request of BT connection link generated, for example, by the BT cellular phone that has just been turned on, while the handsfree apparatus is having an A2DP link with the BT audio player for continuously playing back the music streaming data transferred from the audio player.
However, in the above-described case, due to the continuous transmission of the page command from the handsfree apparatus to the requesting device, or to the cellular phone in this case, until the cellular phone responds to the command or until the preset time elapses, there may be a problematic situation. That is, in a certain time slot that does not have the packet transfer of the music streaming data from the audio player, the continuous transmission of the page command from the handsfree apparatus causes no problem. However, if the audio player is continuously transferring data packets of the music streaming data in a certain time slot, the BT communication band may be occupied by the transmission of the page command from the handsfree apparatus to the requesting cellular phone, thereby interrupting the music streaming data transferred from the audio player and disabling the reception of the music streaming data by the handsfree apparatus, as shown in FIG. 5. As a result, the user of the handsfree apparatus may be disrupted and discomforted by the interrupted playback of the music performed by the handsfree apparatus.